Field
The present disclosure relates generally methods for forming graphene thin films, and more specifically to a CVD route for directly forming graphene layers directly on dielectric substrates.
Technical Background
Graphene is a two-dimensional allotrope of carbon. The structure of graphene includes a single planar sheet of sp2-hybridized carbon atoms arranged in a densely-packed honeycomb array. The carbon-carbon bond length in graphene is about 0.142 nm. A schematic of a graphene monolayer is shown in FIG. 1.
In essence, graphene is an isolated atomic plane of graphite. As a 2-dimensional crystalline material, graphene has unique properties including high intrinsic mobility (200,000 cm2V−1s−1), Young's modulus (˜1,100 GPa), breaking strength (42 Nm−1), fracture strength (˜125 GPa), thermal conductivity (˜5000 Wm−1K−1), surface area (2,630 m2g−1), and an optical transmittance of ˜97%. With such remarkable properties, graphene has a wide variety of potential applications that range from nano-electromechanical resonators and high-performance field effect transistors to clean energy devices, sensors and antibacterial products.
Graphene was first isolated via mechanical exfoliation of highly-oriented pyrolytic graphite (HOPG). It is now well-known that tiny fragments of graphene sheets are produced whenever graphite is abraded, such as when drawing with a pencil. Graphene can also be obtained via carbon segregation by heating a carbon source such as silicon carbide to high temperature (>1100° C.) at low pressure (˜10−6 Torr) to reduce it to graphene.
The lack of a large-scale synthesis route for the production of high-quality graphene at low cost has substantially hampered its proliferation. Accordingly, it would be advantageous to develop an economical method for forming large area graphene.